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Agricultural productivity relies on a wide range of ecosystem services provided by the soil biota. Sustainable management practices, such as tillage and residue management, can influence structure and function of the soil microbiota, with direct consequences for the associated ecosystem services. Although there is increasing evidence that different tillage regimes alter the soil biological indices, we only have a limited understanding of their temporal changes in a rice (Oryza sativa L.)–wheat (Triticum aestivum L.) cropping system. We evaluated the effects of combinations of tillage, crop residue management and green manuring on soil biological indicators after 5 years of the practising rice–wheat system (RWS). Four main plot treatments in rice included the following: (a) PTRW0, puddled transplanted rice with no wheat straw retained; (b) PTRW25, puddled transplanted rice with 25% anchored wheat stubbles retained; (c) PTRW0 + Sesbania aculeate L. green manure (GM); and (d) PTRW25+GM, puddled transplanted rice with 25% anchored wheat stubbles retained+ GM. There were three subplot treatments in the subsequent wheat crop: (a) CTWR0, conventional tillage wheat with rice residue removed; (b) ZTWR0, zero tillage wheat with rice residue removed; and (c) ZTWR100, ZTW with 100% rice residue retained as mulch. The PTRW25+GM treatment, followed by ZTWR100, significantly increased soil microbial biomass carbon, basal soil respiration, microbial quotient and mineralization quotient measured during wheat‐growing season. These biological indicators were higher at vigorous vegetative wheat growth stage than at flowering stage and decreased at maturity. The principal component analysis of the assayed variables showed that all the variables significantly contributed to the variability in parameters examined and were more related to maximum tillering stage of wheat growth than to maturity or at sowing of wheat. Three highly effective biological indicators were microbial biomass carbon, microbial quotient and mineralization quotient, which responded significantly to changes in tillage and residue management practices in the RWS. We conclude that crop residues and green manure have significant to improve soil biochemical processes by improving soil organic carbon and soil biological indicators in rice–wheat cropping system. [ABSTRACT FROM AUTHOR]

The rice-wheat system (RWS) practiced in northwestern parts of the Indo-Gangetic plains of India is highly productive, but conventional practices are resource (water, labour and energy) and cost intensive. A 4-year field study evaluated the effects of green manure (GM), crop residue and tillage on crop yields, economic profitability and soil fertility in a RWS. Four main plot treatments in rice included combinations of wheat stubble and Sesbania aculeata GM management: (1) puddled transplanted rice (PTR) with no wheat stubble, (2) PTR with 25% wheat stubbles (15-20 cm high) retained, (3) PTR with no wheat stubble plus GM, and (4) PTR with wheat stubble splus GM. Three sub-plots treatments in subsequent wheat included (1) conventional till wheat with rice straw removed (CTWR0), (2) zero till wheat with rice straw removed (ZTWR0) and (3) zero till wheat with 100% rice straw retained as surface mulch (ZTWR100). The results showed that main rice yield was significantly higher (8.0%) with 50% less fertilizer N application in GM compared with conventional PTR with no GM. Rice treatments did not affect the grain yield of subsequent wheat. ZTWR100 produced significantly higher mean wheat grain yield by 7.3% and 17.5% compared with CTWR0 and ZTWR0, respectively. System productivity was 11.5% higher in PTR with wheat stubble + GM followed by ZTWR100 compared with the conventional RWS and resulted in Rs 24,075 ha−1 more net returns. Significant increases in soil organic carbon, available P and available K contents were recorded in ZTWR100 over CTWR0. Recycling rice and wheat stubble in the field in RWS is also environment friendly as it avoids ill effects of straw burning. [ABSTRACT FROM AUTHOR]

Dry direct-seeded aerobic rice (DSR) is an emerging attractive alternative to traditional puddled transplanted rice (PTR) production system for reducing labour and irrigation water requirements in the Indo-Gangetic plains (IGP) of India. The fertilizer N requirement of DSR grown with alternate wetting and drying water management may differ from that of PTR grown under continuous flooding due to differences in N dynamics in the soil/water system and crop growth patterns. Limited studies have been conducted on optimizing N management and application schedule for enhanced N use efficiency in DSR. Therefore, field experiments were conducted over 3 years in NW India to evaluate the effects of N rate and timing of its application on crop performance and N use efficiency. Interaction effects of four N rates (0, 120, 150, and 180 kg ha−1) as urea and four schedules of N application on yield and N use efficiency were evaluated in DSR. The N schedules included N application in three equal split doses (0, 35 and 63, and 14, 35 and 63 days after sowing, DAS) and four equal split doses (0, 28, 49 and 70; 14, 28, 49 and 70 DAS). There was no significant interaction between N rate and schedules on grain yield. Significant response to fertilizer N was observed at 120 kg N ha−1and economic optimum dose for three equal split doses and skipping N at sowing was 130 kg N ha−1. Highest mean grain yield of 6.60 t ha−1was obtained when N was applied in three equal split doses at 14, 35 and 63 DAS which was about 8.5% higher compared with N applied in four equal split doses at 14, 28, 49 and 70 DAS. Under the best N application schedule, agronomic N use efficiency (26 kg grain kg−1), recovery efficiency (49%) and physiological efficiency (53 kg kg−1) were comparable to the values reported in Asia for PTR. Results from our study will help to achieve high yields and N use efficiency in DSR to replace resource intensive PTR. [ABSTRACT FROM AUTHOR]

Field experiments were conducted for two years to find out the appropriate sowing configuration and rate of nitrogen (N) for sustained yield and improved water use efficiency of hybrid Bt cotton irrigated through surface drip irrigation. Drip irrigation under normal sowing, in which equal quantities of water and N were applied as check-basin irrigation, resulted in an increase of 389 and 155 kg ha−1 in seed cotton yield compared with check-basin irrigation during the first and second year, respectively. Normal paired row sowing under a drip irrigation system, in which only 50% of irrigation water was applied compared with normal sowing, produced a yield similar to normal sowing under drip irrigation during both years, resulting in 22% higher water use efficiency. Dense paired row sowing under drip irrigation, in which only 75% irrigation water was applied compared with normal sowing, increased the mean seed cotton yield by 5% and water use efficiency by 19%. Decrease in the rate of nitrogen application (from 150 to 75 kg N ha−1) caused a decline in seed cotton yield and water use efficiency under all the methods of sowing, but the reverse was true for agronomic efficiency of N. [ABSTRACT FROM PUBLISHER]